The Raman spectra of cadmium iodide

Raman scattering experiments on polytype CdI2 single crystals have been carried out. A very narrow band – not found before – was detected at 15.8 cm−1 and assigned to the E2 mode of the polytype 4H with space group C . Two further bands at 45.1 and 111.3 cm−1 are assigned to E and A modes respectively from vibrations of the polytypes with C , C and D symmetry. Calculated symmetry coordinates, intensity and halfbandwidth considerations support the proposed assignment. Comparision of the frequencies of the A1 and E1 modes in single crystals of the cadmium halides CdCl2, CdBr2 and CdI2 show very similar bond forces between the cadmium and halogen layers.